1. Field of the Invention
The present invention relates to gas discharge display devices and methods of making the same.
2. Related Art
Technology involved in the present invention is an outgrowth of the neon sign industry. Early neon tubes, developed around 1909, consisted of a length of glass tubing which was fitted with electrodes at its extreme ends. These tubes were evacuated and back filled with ionizable gasses at lower than atmospheric pressures. These gasses were energized with a high voltage signal from a constant current transformer, the signal being of several thousand volts, alternating current, usually line frequency, for example, 50 or 60 cycles per second. The first tubes were filled with carbon dioxide. However, these tubes had to be recharged every few days because the carbon dioxide tended to break down. The tubes were improved by using rare gasses, such as neon. Neon, with its distinctive red color which pierces fog and haze, quickly became popular for providing a dramatic effect in signs and beacons.
Volrath describes a gas filled tube device, in U.S. Pat. No. 1,851,532 (issued Mar. 29, 1932), wherein a filling material was packed inside a conventional neon tube creating a multiple maze of paths for the discharge to follow. A 60 cycle current turned the discharge off and on forcing it to reestablish a path with each cycle and resulting in a dramatic visual effect. Various structures have been disposed inside gas filled tubes, such as porcelain ribbed dividers or multiple tubes, for creating multiple paths for the discharge to follow.